The University could possibly strike dangerous contaminants if it prepares to build a proposed on-campus football stadium, according to Minnesota Pollution Control Agency documents.

The contaminants could include creosote, petroleum or an assortment of industrial wastes.

An environmental assessment of the site will begin soon. University officials could award the contract to conduct a $1.5 million assessment of the stadium site as early as Thursday, according to a tentative University schedule.

Scott Ellison, assistant athletics director, said two companies successfully responded to the University’s request for proposals to study the stadium site’s environmental issues.

The companies will be interviewed by University officials Wednesday, he said.

The state agency’s documents show the stadium site was formerly occupied by an asphalt plant, a bulk petroleum facility, a creosote facility and a rail yard. Creosote can cause cancer and is produced from wood or coal tar.

Gerald Stahnke, Minnesota Pollution Control Agency project manager, said there are a few ways to treat creosote-contaminated soil.

One method – known as “thermal desorption” – would use a machine similar to a stainless steel oven to bake the contaminants out of the soil. Other methods are simpler, such as trucking the soil to a landfill or industrial waste facility. The soil could be left where it is if officials determine it does not pose an environmental threat.

“Thermal desorption is more of a permanent remedy, because it minimizes the University’s liability (for the pollution),” he said. “And it’s fairly cost-effective, if they can do it in one pass.”

The assessments – the environmental assessment worksheet and the environmental impact statement – will determine what the University needs to do to prepare the site for construction.

Polluted groundwater, possibly stemming from the site of the creosote contamination, was found in 1997 while the University constructed the bikeway along Sixth Street Southeast.

The agency’s documents suggest that some of the contamination came from the creosote facility, which operated from 1917-19. The creosote is unlikely to affect any drinking water in the area, but it could cause harm to workers who unearth it, according to the agency’s documents.

Besides creosote, the University might also have to clean up asphalt, petroleum or other industrial contaminants at the stadium site.

Mike Rafferty, Minnesota Pollution Control Agency public information officer, said petroleum can sometimes break down naturally in soil. If the soil is too saturated with petroleum, it needs to be removed or treated, he said.